a2b invokes conversion tools in sequence to convert files from one type to another, possibly performing some extra processing along the way. Itis a wrapper for many programs like gif2png, latex2html, netpbm, mencoder, ffmpeg, oggenc, etc., that can convert content from one type to another. It can covert text, documents, images, audio, and video and more. Some examples: a2b test.mp3 test.ogg; mencoder_opts="-ss 60 -endpos 10" a2b video.avi clip.flv; a2b -g=subtitles dvd://8 movie.sub; a2b -q http://sam.nipl.net/ sam.aac. That last example downloads the author's Web page, converts it to text with lynx -dump, speaks the text with flite or espeak, and converts the audio file to AAC with faac.

SpamCheetah is a network-level spam filtering solution built around OpenBSD greylisting, tarpit, and blacklisting. It comes with a Web interface and requires zero administration. It does not allow spam to even land in your network, thus saving you precious bandwidth. It does not have the 'false positives' problem of losing legitimate mail.

xtxt2typ is a small Ruby script to convert a (minimally prepared, therefore the x-txt2typ) ASCII file into a gtypist lesson. This allows you to learn touch typing while interested in the text you type.

Voynex Email Guard is a JavaScript script designed to protect email addresses on a Web site from email harvesting software while making this protection transparent (invisible) for the Web site visitor. Users can still click, copy, and paste email addresses without knowing that the email address on the Web site is encrypted. Voynex Email Guard transforms email addresses on a Web page into a format that is unreadable for email harvester robots, but makes these addresses readable again for Web site visitors.

filterunit allows unit tests to be devised for command line programs that use files as input and output. Classic Unix filters are a typical example. filterunit runs the program under test with the specified input files and compares the actual results with the expected results.

Rspamd is an anti-spam system designed to work faster than SpamAssassin by using the event model and various optimizations. Its most important features include regexp and Lua rules for filtering different parts of messages, a number of built-in functions for analyzing messages, fuzzy hash support, SURBL filters, email and character table support, a control interface for remote managing and stats gathering, a Lua plugin system, statistics support (OSB/Bayes), and an AJAX-based Web interface.

CacheGuard Appliance is an all-in-one OS appliance providing firewall, antivirus, caching, compression, bandwidth allocation, load balancing, reverse and forward proxy, high availability, Web application firewall, URL guarding, and more. It can be purchased as an OS to install on your server, as an OS to run in a virtual machine, or as a hardware appliance.

ufdbGuard is a URL filter. The URL filter blocks access to sets of Web sites and cooperates with the Squid proxy. It integrates with LDAP, Kerberos, Active Directory, MySQL, and others to define different ploicies for different groups of users. ufdbGuard also enforces SafeSearch for many search engines, blocks Skype, UltraSurf, Tor, unsafe HTTPS sites, and dynamically detects proxy tunnels. The multi-threaded daemon uses a fast algorithm that does 50,000 URL verifications per second on an Intel Core 2 Duo (Conroe) at 2.4 GHz.

eLyXer (pronounced elixir) is a LyX to HTML converter. While there are a ton of such projects all over the Web, eLyXer has a clear focus on flexibility and elegant output. LyX is a wonderful text editor that produces beautiful PDF files. Internally, it exports documents to LaTeX, and from there to PDF. Sadly there is not an equivalent “export to HTML” option. With eLyXer, you can convert your master’s thesis, learned article, fascinating novel, or love letter to an HTML page that you can then publish on the Web. It is a standalone tool that does not depend on LyX.